The invention relates to a portable bandsaw mill, which can conveniently be operated on logs at a felling site.
A so-called portable saw mill is disclosed in U.S. Pat. No. 1,238,436 issued on Aug. 28, 1917 to R. P. Reece. The Reece saw mill is however a complex and massive structure adapted to be transported by a team of horses, and designed so that the ground supported frame, on which a carriage for the saw travels, cannot be located so as to straddle a felled tree trunk.
A more compact and portable bandsaw mill is disclosed in U.S. Pat. No. 3,721,146 issued to Charles E. MacNamana on Mar. 20, 1973. A base with clamping means for engaging a log to be sawn supports by means of U-shaped cross bars a pair of rails on which a horizontal bandsaw travels. A crank screw connection between the rails and the base permits the level of the rails to be adjusted. The base must be located beneath the log, or the log moved on to the base, and no adjustment to take into account uneven ground surfaces is provided. Moreover, the bandsaw moves on the rails by way of guides which would be liable to jamming.
A different approach is disclosed in Patent Application GB No. 2 009 037 A by A. J. Dunstan. Here, a horizontal bandhead is supported by a wheeled trolley rolling on the block to be sawn. A constant force mechanism urges the bandhead upwardly on the trolley to counterbalance its weight. Such a saw mill is necessarily of considerable weight and must be lifted by its operators between each cut.
It is an object of the invention to provide a portable bandsaw mill which is in a form to facilitate transportation to the site at which it is to be used.
It is also an object of the invention to provide a portable bandsaw mill which can be readily assembled for use and which allows accurate sawing operations to be conveniently and reliably performed.
It is a further object of the invention to provide a portable bandsaw mill in which the weight of the saw unit is supported from the ground and in which the sawing operation remains fully under operator control.
It is a further object of the invention to provide a portable bandsaw mill including a support unit for the saw unit which can be readily adjusted to accommodate irregularities of the ground surface at the site.
It is additionally an object of the invention to provide supporting guide means for a traversing saw unit in a portable bandsaw mill which enable the level of the cut to be readily adjusted.
It is a further object of the invention to provide a portable bandsaw mill in which operators can readily feed the saw unit through a log to be planked whilst retaining complete control to accommodate for irregularities in the log.
It is a further object of the invention to provide a bandsaw mill having a simple and effective saw blade tensioning device.
It is additionally an object of the invention of the invention to provide a bandsaw mill having means for facilitating replacement of the saw blade.
It is a further object of the present invention to provide a bandsaw mill comprising components which can be readily disassembled for transportation and readily assembled in working relationship to felled timber.
It is a further object of the invention to provide a portable bandsaw mill in which a manually movable saw unit is supported in a manner permitting safe operation and efficient cutting of the work.